9. Strait Co. manufactures office furniture. During the most productive month of the year, 3,200 desks were manufactured at a total cost of $84,400. In the month of lowest production the company made 1,120 desks at a cost of $55,200. Using the high-low method of cost estimation, total fixed costs are

a.$55,200

b.$39,472

c.$84,400

d.$29,200